The present invention relates to a belt tightener for vehicle safety belt systems comprising a belt tightener drive and mechanical gripping means for engaging a belt webbing section upon activation of the tightener drive.
In a safety belt system of this type which is known from German Offenlegungsschrift 34 13 488, the gripping means is connected via a tension transmitting element to the tightener drive. The end of the tension transmitting element remote from the gripping means is connected to the piston of a return blocking means having a cylinder which is secured to the vehicle bodywork. The piston is displaceable within the cylinder in unrestricted manner in the tightening direction but in the opposite direction is blocked.